The class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon has been known for some time. Nozaki, e.g., U.S. Pat. No. 3,694,412, produced such polymers in the presence of arylphosphine complexes of palladium moieties and certain inert solvents. More recent methods of producing such polymers are illustrated by a number of published European Patent Applications including Nos. 121,965, 181,014, 213,671 and 257,663. The processes involve polymerization in the presence of a catalyst formed from a compound of palladium, cobalt or nickel, the anion of a strong non-hydrohalogenic acid and a bidentate ligand of phosphorus, arsenic, antimony or nitrogen.
The linear alternating polymers, now known as polyketones or polyketone polymers, are relatively high molecular weight materials having established utility as premium thermoplastics. They are processed by methods conventional for thermoplastic polymers such as extrusion, injection molding and thermoforming into a variety of shaped articles such as containers for food or drink.
One method of polymerizing the carbon monoxide and at least one ethylenically unsaturated hydrocarbon comprises a batch process in a suitable reactor which is preferably equipped with some agitation means to promote reactant/catalyst contact. In such a process the reactants, catalyst composition and a reaction diluent are charged to the reactor and maintained under polymerization conditions. In an alternate semi-continuous process, reactants are continuously charged to the reactor until the viscosity of the resulting suspension of polymer product in the reaction diluent becomes too great to permit efficient heat removal. At this point, the reaction is terminated and the polymer suspension is removed.
A problem particularly associated with such batch or semi-continuous operation is a tendency toward reactor fouling. During the polymerization, there is a tendency for polymer to deposit upon the inner surfaces of the reactor such as the reactor walls, baffles, stirrer blades, stirring shaft and cooling and heating coils. This deposited polymer is difficult to remove by methods such as washing with reaction diluent. It is frequently necessary to employ mechanical methods. The reactor fouling can be as high as 50% or greater and is a substantial detriment to commercial operation of the process. It would be of advantage to provide a method of producing the linear alternating polymers with less reactor fouling.